Ours is a parliamentary democracy and the resolution to go to war was determined by our political representatives.As the decision was a shared one, the blame also must be shared.Given
that vast numbers of innocents are dead as a consequence of the
invasion it is not sufficient for those responsible to claim they were
duped.

They're certainly correct about their type of government.

And I do agree that many share blame. I would include Gordon Brown (who
replaced Blair as prime minister and could have ended the UK
involvement much sooner), I would include Barack Obama who has not ended
the Iraq War despite being elected on the promise that he would. I
would include members of the US Congress such as Hillary Clinton who
voted for it. I would include members of Congress who pretended to be
against it but did nothing to stop it once it started -- US House Rep
Barbara Lee poses so well she should be in a wax museum, not in
Congress. Former US Senator Mike Gravel in 2007 and 2008 repeatedly
outlined how anyone in Congress could stop the war. (Gravel was not in
Congress during the Iraq War.) I would include a lot of people.

But of all of them: Bully Boy Bush and Tony Blair would be at the top.
(Barack would be immediately below them because the Iraq War goes on.)

As for who would be at the top?

Tony Blair.

Bully Boy Bush was a laughingstock on the world stage.

He needed Blair as an ally to sell the war.

The so-called coalition of the willing would have been next to nothing without Blair.

Blair had an image -- a false one, but an image -- for being upstanding and forthright.

Blair was deceitful and a liar -- as most of New Labour is and was.

He sold out the people in one neoliberal scheme after another.

But he could have held onto the myth were it not for the Iraq War.

Had he not made the promise long before the war started -- as documented
in the report from the Iraq Inquiry -- to stand with Bully Boy Bush no
matter what, it's very possible the war would not have started.

France already was thought unwilling to take part (the report throws
doubt on Blair and Bush's assumptions there). To have also not had the
longterm ally of England?

It would have been much harder to get the war off the ground.

The war machine in the US -- which does include the media, never forget that:

The war machine had already slimed the French. If they had then done
the same with the British, late night comics would have had a field day
with who was next and Americans would have been even more suspicious of
the impending war.

Bully Boy Bush was seen as a deranged cowboy.

Blair was seen as a wise and thoughtful leader.

Without Blair by his side, a case can be made that the Iraq War would not have started.